Leukemia: A Transition From Basic Science to Clinical Practice.

The term "leukemia" actually refers to a family of blood cancers, each having a distinct pattern of symptoms and cytology and each differing in age of onset, prognosis, and therapeutic options. The acute leukemias -acute myelogenous leukemia (AML) and acute lymphoblastic leukemia (ALL) -have been recognized for their rapid clinical progression when untreated and are diagnosed by the identification of primitive, poorly differentiated hematopoietic precursors (blasts) in the blood and bone marrow. The chronic leukemias are more heterogeneous and also include myeloid and lymphoid disorders. Chronic myelogenous leukemia (CML), a relatively indolent disorder that is most common in young adults, is characterized by a proliferation of mature and immature myeloid precursors. CML gives rise to high peripheral blood white counts and splenomegaly. The chronic lymphoid leukemias, of which chronic lymphocytic leukemia (CLL) and hairy cell leukemia are the most common, are generally disorders of mid to late adulthood. They are usually indolent but, in many cases, may not be curable with conventional therapy. Patients will have variable numbers of circulating malignant lymphoid cells. The degree of splenomegaly, lymphadenopathy, and bone marrow involvement will depend on the subtype of leukemia diagnosed.